Methods to make capacitors containing a partially reduced niobium metal oxide

ABSTRACT

Methods to at least partially reduce a niobium oxide are described wherein the process includes heat treating the niobium oxide in the presence of a getter material and in an atmosphere which permits the transfer of oxygen atoms from the niobium oxide to the getter material, and for a sufficient time and at a sufficient temperature to form an oxygen reduced niobium oxide. Niobium oxides and/or suboxides are also described as well as capacitors containing anodes made by fabricating a pellet of niobium oxide and heat treating the pellet in an atmosphere which permits the transfer of oxygen to a getter material, and for a sufficient time and temperature to form an electrode body, and anodizing the electrode body.

This application is a divisional application of U.S. patent applicationSer. No. 09/347,990 filed Jul. 6, 1999, now U.S. Pat. No. 6,416,730,which is a continuation-in-part of U.S. patent application Ser. No.09/154,452 filed Sep. 16, 1998, now U.S. Pat. No. 6,391,275, and U.S.patent application Ser. No. 60/100,629 filed Sep. 16, 1998, which areboth incorporated herein in their entirety by reference.

BACKGROUND OF THE INVENTION

The present invention relates to niobium and oxides thereof and moreparticularly relates to niobium oxides and methods to at least partiallyreduce niobium oxide and further relates to oxygen reduced niobium.

SUMMARY OF THE PRESENT INVENTION

In accordance with the purposes of the present invention, as embodiedand described herein, the present invention relates to a method to atleast partially reduce a niobium oxide which includes the steps of heattreating the niobium oxide in the presence of a getter material and inan atmosphere which permits the transfer of oxygen atoms from theniobium oxide to the getter material for a sufficient time andtemperature to form an oxygen reduced niobium oxide.

The present invention also relates to oxygen reduced niobium oxideswhich preferably have beneficial properties, especially when formed intoan electrolytic capacitor anode. For instance, a capacitor made from theoxygen reduced niobium oxide of the present invention can have acapacitance of up to about 200,000 CV/g or more. Further, electrolyticcapacitor anodes made from the oxygen reduced niobium oxides of thepresent invention can have a low DC leakage. For instance, such acapacitor can have a DC leakage of from about 0.5 nA/CV to about 5.0nA/CV.

Accordingly, the present invention also relates to methods to increasecapacitance and reduce DC leakage in capacitors made from niobiumoxides, which involves partially reducing a niobium oxide by heattreating the niobium oxide in the presence of a getter material and inan atmosphere which permits the transfer of oxygen atoms from theniobium oxide to the getter material, for a sufficient time andtemperature to form an oxygen reduced niobium oxide, which when formedinto a capacitor anode, has reduced DC leakage and/or increasedcapacitance.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are intended to provide further explanation of the presentinvention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-11 are SEMs of various oxygen reduced niobium oxides of thepresent invention at various magnifications.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

In an embodiment of the present invention, the present invention relatesto methods to at least partially reduce a niobium oxide. In general, themethod includes the steps of heat treating a starting niobium oxide inthe presence of a getter material in an atmosphere which permits thetransfer of oxygen atoms from the niobium oxide to the getter materialfor a sufficient time and at a sufficient temperature to form an oxygenreduced niobium oxide.

For purposes of the present invention, the niobium oxide can be at leastone oxide of niobium metal and/or alloys thereof. A specific example ofa starting niobium oxide is Nb₂O₅.

The niobium oxide used in the present invention can be in any shape orsize. Preferably, the niobium oxide is in the form of a powder or aplurality of particles. Examples of the type of powder that can be usedinclude, but are not limited to, flaked, angular, nodular, and mixturesor variations thereof. Preferably, the niobium oxide is in the form of apowder which more effectively leads to the oxygen reduced niobium oxide.

Examples of such preferred niobium oxide powders include those havingmesh sizes of from about 60/100 to about 100/325 mesh and from about60/100 to about 200/325 mesh. Another range of size is from −40 mesh toabout −325 mesh. In other words, the preferred niobium oxide powdershave particle sizes from about 150/250 to about 45/150 microns, and fromabout 150/250 to about 45/75 microns. Another preferred size range isfrom about 355 microns to about 45 microns.

The getter material for purposes of the present invention is anymaterial capable of reducing the specific starting niobium oxide to theoxygen reduced niobium oxide. Preferably, the getter material comprisestantalum, niobium, or both. Other examples include, but are not limitedto, magnesium and the like. Any getter material that has a greateraffinity for oxygen than niobium oxide can be used. More preferably, thegetter material is niobium. The niobium getter material for purposes ofthe present invention is any material containing niobium metal which canremove or reduce at least partially the oxygen in the niobium oxide.Thus, the niobium getter material can be an alloy or a materialcontaining mixtures of niobium metal with other ingredients. Preferably,the niobium getter material is predominantly, if not exclusively,niobium metal. The purity of the niobium getter material is notimportant but it is preferred that high purity niobium comprise thegetter material to avoid the introduction of other impurities during theheat treating process. Accordingly, the niobium metal in the niobiumgetter material preferably has a purity of at least about 98% and morepreferably at least about 99%. Oxygen levels in the niobium gettermaterial can be any amount. Preferably, impurities that affect DCleakage, such as iron, nickel, chromium, and carbon, are below about 100ppm. Most preferably, the getter material is a niobium flake metalpreferably having a high capacitance capability, such as greater thanabout 75,000 Cv/g and more preferably about 100,000 Cv/g or higher, suchas about 200,000 Cv/g. The getter material also preferably has a highsurface area, such as a BET of from about 5 to about 30 m²/g and morepreferably from about 20 to about 30 m²/g.

The getter material can be in any shape or size. For instance, thegetter material can be in the form of a tray which contains the niobiumoxide to be reduced or can be in a particle or powder size. Preferably,the getter materials are in the form of a powder in order to have themost efficient surface area for reducing the niobium oxide. The gettermaterial, thus, can be flaked, angular, nodular, and mixtures orvariations thereof, e.g., coarse chips, such as 14/40 mesh chips thatcan be easily separated from the powder product by screening.

Similarly, the getter material can be tantalum and the like and can havethe same preferred parameters and/or properties discussed above for theniobium getter material. Other getter materials can be used alone or incombination with the tantalum or niobium getter materials. Also, othermaterials can form a part of the getter material.

Generally, a sufficient amount of getter material is present to at leastpartially reduce the niobium oxide being heat treated. Further, theamount of the getter material is dependent upon the amount of reducingdesired to the niobium oxide. For instance, if a slight reduction in theniobium oxide is desired, then the getter material will be present in astoichemetric amount. Similarly, if the niobium oxide is to be reducedsubstantially with respect to its oxygen presence, then the gettermaterial is present in a 2 to 5 times stoichemetric amount. Generally,the amount of getter material present (e.g., based on the tantalumgetter material being 100% tantalum) can be present based on thefollowing ratio of getter material to the amount of niobium oxidepresent of from about 2 to 1 to about 10 to 1. The getter material ispreferably blended or mixed together with the starting niobium oxide inan atmosphere which permits the transfer of oxygen atoms from theniobium oxide to the getter material (e.g., a hydrogen atmosphere), andpreferably at a temperature of from about 1100° C. to about 1500° C.

Furthermore, the amount of getter material can also be dependent on thetype of niobium oxide being reduced. For instance, when the niobiumoxide being reduced is Nb₂O₅, the amount of getter material ispreferably 5 to 1. Also, when starting with Nb₂O₅, a stoichiometricamount of getter material, preferably niobium flake metal, is used toachieve an oxide which preferably is 0.89 parts metal to 1 part oxide.

The heat treating that the starting niobium oxide is subjected to can beconducted in any heat treatment device or furnace commonly used in theheat treatment of metals, such as niobium and tantalum. The heattreatment of the niobium oxide in the presence of the getter material isat a sufficient temperature and for a sufficient time to form an oxygenreduced niobium oxide. The temperature and time of the heat treatmentcan be dependent on a variety of factors such as the amount of reductionof the niobium oxide, the amount of the getter material, and the type ofgetter material as well as the type of starting niobium oxide.Generally, the heat treatment of the niobium oxide will be at atemperature of from less than or about 800° C. to about 1900° C. andmore preferably from about 1000° C. to about 1400° C., and mostpreferably from about 1100° C. to about 1250° C. In more detail, whenthe niobium oxide is a niobium containing oxide, the heat treatmenttemperatures will be from about 1000° C. to about 1300° C., and morepreferably from about 1100° C. to about 1250° C. for a time of fromabout 5 minutes to about 100 minutes, and more preferably from about 30minutes to about 60 minutes. Routine testing in view of the presentapplication will permit one skilled in the art to readily control thetimes and temperatures of the heat treatment in order to obtain theproper or desired reduction of the niobium oxide.

The heat treatment occurs in an atmosphere which permits the transfer ofoxygen atoms from the niobium oxide to the getter material. The heattreatment preferably occurs in a hydrogen containing atmosphere which ispreferably just hydrogen. Other gases can also be present with thehydrogen, such as inert gases, so long as the other gases do not reactwith the hydrogen. Preferably, the hydrogen atmosphere is present duringthe heat treatment at a pressure of from about 10 Torr to about 2000Torr, and more preferably from about 100 Torr to about 1000 Torr, andmost preferably from about 100 Torr to about 930 Torr. Mixtures of H₂and an inert gas such as Ar can be used. Also, H₂ in N₂ can be used toeffect control of the N₂ level of the niobium oxide.

During the heat treatment process, a constant heat treatment temperaturecan be used during the entire heat treating process or variations intemperature or temperature steps can be used. For instance, hydrogen canbe initially admitted at 1000° C. followed by increasing the temperatureto 1250° C. for 30 minutes followed by reducing the temperature to 1000°C. and held there until removal of the H₂ gas. After the H₂ or otheratmosphere is removed, the furnace temperature can be dropped.Variations of these steps can be used to suit any preferences of theindustry. The oxygen reduced niobium oxides can be subsequently reducedin size such as by crushing. The oxygen reduced niobium oxides can beagglomerated and crushed or processed in any other way that valve metalscan be processed.

The oxygen reduced niobium oxides can also contain levels of nitrogen,e.g., from about 100 ppm to about 30,000 ppm N₂.

The oxygen reduced niobium oxide is any niobium oxide which has a loweroxygen content in the metal oxide compared to the starting niobiumoxide. Typical reduced niobium oxides comprise NbO, NbO_(0.7),NbO_(1.1), NbO₂, and any combination thereof with or without otheroxides present. Generally, the reduced niobium oxide of the presentinvention has an atomic ratio of niobium to oxygen of about 1:less than2.5, and preferably 1:2 and more preferably 1:1.1, 1:1, or 1:0.7. Putanother way, the reduced niobium oxide preferably has the formulaNb_(x)O_(y), wherein Nb is niobium, x is 2 or less, and y is less than2.5x. More preferably x is 1 and y is less than 2, such as 1.1, 1.0,0.7, and the like.

The starting niobium oxides can be prepared by calcining at 1000° C.until removal of any volatile components. The oxides can be sized byscreening. Preheat treatment of the niobium oxides can be used to createcontrolled porosity in the oxide particles.

The reduced niobium oxides of the present invention also preferably havea microporous surface and preferably have a sponge-like structure,wherein the primary particles are preferably 1 micron or less. The SEMsfurther depict the type of preferred reduced niobium oxide of thepresent invention. As can be seen in these microphotographs, the reducedniobium oxides of the present invention can have high specific surfacearea, and a porous structure with approximately 50% porosity. Further,the reduced niobium oxides of the present invention can be characterizedas having a preferred specific surface area of from about 0.5 to about10.0 m²/g, more preferably from about 0.5 to 2.0 m²/g, and even morepreferably from about 1.0 to about 1.5 m²/g. The preferred apparentdensity of the powder of the niobium oxides is less than about 2.0 g/cc,more preferably, less than 1.5 g/cc and even more preferably, from about0.5 to about 1.5 g/cc. Also, the powder of the niobium oxides can haveScott densities, such as from about 5 g/in³ to about 35 g/in³.

The various oxygen reduced niobium oxides of the present invention canbe further characterized by the electrical properties resulting from theformation of a capacitor anode using the oxygen reduced niobium oxidesof the present invention. In general, the oxygen reduced niobium oxidesof the present invention can be tested for electrical properties bypressing powders of the oxygen reduced niobium oxide into an anode andsintering the pressed powder at appropriate temperatures and thenanodizing the anode to produce an electrolytic capacitor anode which canthen be subsequently tested for electrical properties.

Accordingly, another embodiment of the present invention relates toanodes for capacitors formed from the oxygen reduced niobium oxides ofthe present invention. Anodes can be made from the powdered form of thereduced oxides in a similar process as used for fabricating metalanodes, i.e., pressing porous pellets with embedded lead wires or otherconnectors followed by optional sintering and anodizing. The leadconnector can be embedded or attached at any time before anodizing.Anodes made from some of the oxygen reduced niobium oxides of thepresent invention can have a capacitance of from about 1,000 CV/g orlower to about 300,000 CV/g or more, and other ranges of capacitance canbe from about 20,000 CV/g to about 300,000 CV/g or from about 62,000CV/g to about 200,000 CV/g and preferably from about 60,000 to 150,000CV/g. In forming the capacitor anodes of the present invention, asintering temperature can be used which will permit the formation of acapacitor anode having the desired properties. The sintering temperaturewill be based on the oxygen reduced niobium oxide used. Preferably, thesintering temperature is from about 1200° C. to about 1750° C. and morepreferably from about 1200° C. to about 1400° C. and most preferablyfrom about 1250° C. to about 1350° C. when the oxygen reduced niobiumoxide is an oxygen reduced niobium oxide.

The anodes formed from the niobium oxides of the present invention arepreferably formed at a voltage of about 35 volts and preferably fromabout 6 to about 70 volts. When an oxygen reduced niobium oxide is used,preferably, the forming voltages are from about 6 to about 50 volts, andmore preferably from about 10 to about 40 volts. Other high formationvoltages can be used. Anodes of the reduced niobium oxides can beprepared by fabricating a pellet of Nb₂O₅ with a lead wire followed bysintering in H₂ atmosphere or other suitable atmosphere in the proximityof a getter material just as with powdered oxides. In this embodiment,the anode article produced can be produced directly, e.g., forming theoxygen reduced valve metal oxide and an anode at the same time. Also,the anodes formed from the oxygen reduced niobium oxides of the presentinvention preferably have a DC leakage of less than about 5.0 nA/CV. Inan embodiment of the present invention, the anodes formed from some ofthe oxygen reduced niobium oxides of the present invention have a DCleakage of from about 5.0 nA/CV to about 0.50 nA/CV.

The present invention also relates to a capacitor in accordance with thepresent invention having a niobium oxide film on the surface of thecapacitor. Preferably, the film is a niobium pentoxide film. The meansof making metal powder into capacitor anodes is known to those skilledin the art and such methods such as those set forth in U.S. Pat. Nos.4,805,074, 5,412,533, 5,211,741, and 5,245,514, and European ApplicationNos. 0 634 762 A1 and 0 634 761 A1, all of which are incorporated intheir entirety herein by reference.

The capacitors of the present invention can be used in a variety of enduses such as automotive electronics, cellular phones, computers, such asmonitors, mother boards, and the like, consumer electronics includingTVs and CRTs, printers/copiers, power supplies, modems, computernotebooks, disc drives, and the like.

The present invention will be further clarified by the followingexamples, which are intended to be exemplary of the present invention.

TEST METHODS

Anode Fabrication

size—0.197″ dia

3.5 Dp

powder wt=341 mg

Anode Sintering

1300 Deg C.* 10′

1450 Deg C.* 10′

1600 Deg C.* 10′

1750 Deg C.* 10′

30V Ef Anodization

30V Ef @ 60 Deg C./0.1% H₃PO₄ Electrolyte

20 mA/g constant current

DC Leakage/Capacitance—ESR Testing:

DC Leakage Testing

70% Ef (21 VDC) Test Voltage

60 second charge time

10% H₃PO₄ @ 21 Deg C.

Capacitance—DF Testing

18% H₂SO₄ @ 21 Deg C.

120 Hz

50V Ff Reform Anodization

50V Ef @ 60 Deg C./0.1% H₃PO₄ Electrolyte

20 mA/g constant current

DC Leakage/Capacitance—ESR Testing

DC leakage Testing

70% Ef (35 VDC) Test Voltage

60 second charge time

10% H₃PO₄@ 21 Deg C.

Capacitance—DF Testing

18% H₂SO₄ @ 21 Deg C.

120 Hz

75V Ef Reform Anodization

75V Ef @ 60 Deg C./0.1% H₃PO₄ Electrolyte

20 mA/g constant current

DC Leakage/Capacitance—ESR Testing

DC leakage Testing

70% Ef (52.5 VDC) Test Voltage

60 second charge time

10% H₃PO4 @ 21 Deg C.

Capacitance—DF Testing:

18% H₂SO₄ @ 21 Deg C.

120 Hz

Scott Density, oxygen analysis, phosphorus analysis, and BET analysiswere determined according to the procedures set forth in U.S. Pat. Nos.5,011,742; 4,960,471; and 4,964,906, all incorporated hereby in theirentireties by reference herein.

EXAMPLES Example 1

+10 mesh Ta hydride chips (99.2 gms) with approximately 50 ppm oxygenwere mixed with 22 grams of Nb₂O₅ and placed into Ta trays. The trayswere placed into a vacuum heat treatment furnace and heated to 1000° C.H₂ gas was admitted to the furnace to a pressure of +3 psi. Thetemperature was further ramped to 1240° C. and held for 30 minutes. Thetemperature was lowered to 1050° C. for 6 minutes until all H₂ was sweptfrom the furnace. While still holding 1050° C., the argon gas wasevacuated from the furnace until a pressure of 5×10⁻⁴ torr was achieved.At this point 700 mm of argon was readmitted to the chamber and thefurnace cooled to 60° C.

The material was passivated with several cyclic exposures toprogressively higher partial pressures of oxygen prior to removal fromthe furnace as follows: The furnace was backfilled with argon to 700 mmfollowed by filling to one atmosphere with air. After 4 minutes thechamber was evacuated to 10⁻² torr. The chamber was then backfilled to600 mm with argon followed by air to one atmosphere and held for 4minutes. The chamber was evacuated to 10⁻² torr. The chamber was thenbackfilled to 400 mm argon followed by air to one atmosphere. After 4minutes the chamber was evacuated to 10⁻² torr. The chamber was thembackfilled to 200 mm argon followed by air to one atmosphere and heldfor 4 minutes. The chamber was evacuated to 10⁻² torr. The chamber wasbackfilled to one atmosphere with air and held for 4 minutes. Thechamber was evacuated to 10⁻² torr. The chamber was backfilled to oneatmosphere with argon and opened to remove the sample. The powderproduct was separated from the tantalum chip getter by screening througha 40 mesh screen. The product was tested with the following results.

CV/g of pellets sintered to 1300° C. X 10 minutes and formed to 35 volts= 81,297 nA/CV (DC leakage) = 5.0 Sintered Density of pellets = 2.7 g/ccScott density = 0.9 g/cc Chemical Analysis (ppm) C = 70 H₂ = 56 Ti = 25Fe = 25 Mn = 10 Si = 25 Sn = 5 Ni = 5 Cr = 10 Al = 5 Mo = 25 Mg = 5 Cu =50 B = 2 Pb = 2 all others < limits

Example 2

Samples 1 through 20 are examples following similar steps as above withpowdered Nb₂O₅ as indicated in the Table. For most of the examples, meshsizes of the starting input material are set forth in the Table, forexample 60/100, means smaller than 60 mesh, but larger than 100 mesh.Similarly, the screen size of some of the Ta getter is given as 14/40.The getters marked as “Ta hydride chip” are +40 mesh with no upper limiton particle size.

Sample 18 used Nb as the getter material (commercially available N200flaked Nb powder from CPM). The getter material for sample 18 was finegrained Nb powder which was not separated from the final product. X-raydiffraction showed that some of the getter material remained as Nb, butmost was converted to NbO_(1.1), and NbO by the process as was thestarting niobium oxide material Nb₂O₅.

Sample 15 was a pellet of Nb₂O₅, pressed to near solid density, andreacted with H₂ in close proximity to the Ta getter material. Theprocess converted the solid oxide pellet into a porous slug of NbOsuboxide. This slug was sintered to a sheet of Nb metal to create ananode lead connection and anodized to 35 volts using similar electricalforming procedures as used for the powder slug pellets. This sampledemonstrates the unique ability of this process to make a ready toanodize slug in a single step from Nb₂O₅ starting material.

The Table shows the high capacitance and low DC leakage capability ofanodes made from the pressed and sintered powders/pellets of the presentinvention. Microphotographs (SEMs) of various samples were taken. Thesephotographs show the porous structure of the reduced oxygen niobiumoxide of the present invention. In particular, FIG. 1 is a photograph ofthe outer surface of a pellet taken at 5,000× (sample 15). FIG. 2 is aphotograph of the pellet interior of the same pellet taken at 5,000×.FIGS. 3 and 4 are photographs of the outer surface of the same pellet at1,000×. FIG. 5 is a photograph of sample 11 at 2,000× and FIGS. 6 and 7are photographs taken of sample 4 at 5,000×. FIG. 8 is a photographtaken of sample 3 at 2,000× and FIG. 9 is a photograph of sample 6 at2,000×. Finally, FIG. 10 is a photograph of sample 6, taken at 3,000×and FIG. 11 is a photograph of sample 9 taken at 2,000×.

TABLE XRD* XRD* XRD* XRD* Sam- Temp Time Hydrogen Major Major MinorMinor 1300X35v 1300X35v ple Input Material Gms Input Getter Gms (° C.)(min) Pressure 1** 2** 1*** 2*** CV/g na/CV  1 −40 mesh 20(est) Tahydride chips 40 (est) 1240 30  3 psi  81297  5 calcined Nb₂O₅  2 60/100 Nb₂O₅ 23.4 Ta hydride chips 65.4 1250 30  3 psi NbO_(1.1) NbOTaO 115379  1.28  3  60/100 Nb₂O₃ 23.4 Ta hydride chips 65.4 1250 30  3psi NbO_(1.1) NbO TaO 121293  2.19  4 100/325 Nb₂O₅ 32.3 Ta hydridechips 92.8 1250 30  3 psi 113067  1.02  5 100/325 Nb₂O₅ 32.3 Ta hydridechips 92.8 1250 30  3 psi 145589  1.42  6  60/100 Nb₂O₅ 26.124 Tahydride chips 72.349 1250 90  3 psi  17793 12.86  7  60/100 Nb₂O₅ 26.124Ta hydride chips 72.349 1250 90  3 psi  41525  5.63  8 200/325 Nb₂O₅29.496 Ta hydride chips 83.415 1250 90  3 psi  17790 16.77  9  60/100Nb₂O₅ 20.888 Ta hydride chips 60.767 1200 90  3 psi NbO_(1.1) NbO Ta₂O₃ 63257  5.17 10  60/100 Nb₂O₅ 20.888 Ta hydride chips 60.767 1200 90  3psi NbO_(1.1) NbO Ta₂O₃  69881  5.5 11 200/325 Nb₂O₅ 23.936 Ta hydridechips 69.266 1200 90  3 psi NbO_(1.1) NbO Ta₂O₅  61716  6.65 12 200/325Nb₂O₅ 23.936 Ta hydride chips 69.266 1200 90  3 psi NbO_(1.1) NbO Ta₂O₃ 68245  6.84 13 200/325 Nb₂O₅ 15.5 14/40 Ta hydride 41.56 1250 30  3 psiNbO_(0.7) NbO TaO NbO₂  76294  4.03 14 200/325 Nb₂O₅ 10.25 14/40 Tahydride 68.96 1250 30  3 psi NbO_(0.7) NbO TaO NbO₂  29281 21.03 15Nb₂O₅ pellets  3.49 14/40 Ta hydride 25.7 1250 30  3 psi  70840  0.97 16200/325 Nb₂O₅ 13.2 14/40 Ta hydride 85.7 1200 30  3 psi NbO₂ NbO_(0.7)TaO NbO  5520 34.33 17 200/325 Nb₂O₅ 14.94 14/40 Ta hydride 41.37 120030  3 psi  6719 38.44 18 200/325 Nb₂O₅ 11.92 N200 Nb powder 21.07 120030  3 psi Nb NbO_(1.1) NbO  25716  4.71 19 200/325 Nb₂O₅ 10 14/40 Tahydride 69 1250 30 100 Torr 108478  1.95 20 200/325 Nb₂O₅ 16 14/40 Tahydride 41 1250 30 100 Torr 106046  1.66 *X-Ray Defraction AnalysisResults **Major 1 and 2 refer to primary components present by weight.***Minor 1 and 2 refer to secondary components present by weight.Samples 11 and 12 had the same input material. Samples 2 and 3 had thesame input material. Samples 6 and 7 had the same input material.Samples 9 and 10 had the same input material.

Other embodiments of the present invention will be apparent to thoseskilled in the art from consideration of the specification and practiceof the invention disclosed herein. It is intended that the specificationand examples be considered as exemplary only, with a true scope andspirit of the invention being indicated by the following claims.

What is claimed is:
 1. A method of making a capacitor anode comprisinga) fabricating a pellet of niobium oxide and heat treating the pellet inthe presence of a niobium flaked getter material or magnesium containinggetter material, and in an atmosphere which permits the transfer ofoxygen atoms from the niobium oxide to the niobium flaked gettermaterial or magnesium containing getter material, and for a sufficienttime and temperature to form an electrode body comprising the pellet,wherein the pellet comprises an oxygen reduced niobium oxide, and b)anodizing said electrode body to form said capacitor anode.
 2. Themethod of claim 1, wherein the atmosphere is a hydrogen atmosphere. 3.The method of claim 1, wherein the getter material is flaked niobium. 4.The method of claim 1, wherein the oxygen reduced niobium oxide has anatomic ratio of niobium to oxygen of 1:less than 2.5.
 5. The method ofclaim 1, wherein the niobium oxide is a niobium pentoxide.
 6. The methodof claim 1, wherein the oxygen reduced niobium oxide is a niobiumsuboxide.
 7. The method of claim 1, wherein the oxygen reduced niobiumoxide has oxygen levels that are less than stoichemetric for a fullyoxidized niobium.
 8. The method of claim 1, wherein the oxygen reducedniobium oxide has a micro-porous structure.
 9. The method of claim 1,wherein the oxygen reduced niobium oxide has a pore volume of about 50%.10. The method of claim 1, wherein the atmosphere is hydrogen and ispresent in an amount of about 10 Torr to about 2000 Torr.
 11. The methodof claim 1, wherein the niobium flaked getter material is capable of acapacitance of at least 75,000 Cv/g when formed into an anode.
 12. Themethod of claim 1, wherein the niobium flaked getter material is capableof a capacitance of at least about 100,000 Cv/g when formed into ananode.
 13. The method of claim 1, wherein the niobium flaked gettermaterial is capable of a capacitance of from about 120,000 Cv/g to about200,000 Cv/g when formed into an anode.
 14. The method of claim 1,wherein said heat treating is at a temperature of from about 1100° C. toabout 1500° C. and for about 10 to about 90 minutes.
 15. The method ofclaim 1, wherein said niobium flaked material is homogenized with theniobium oxide prior to or during the heat treating step.